backup: before Variant B selective socket/client/link reload impl

lib/debug_config.c

@@ -297,6 +297,19 @@ void debug_disable_file_output(void) {
     }
 }
 
+/* Reopen log file (append mode) for SIGHUP. Complete operation with full error logging. */
+int debug_reopen_log(void) {
+    if (!g_debug_config.output_file) {
+        DEBUG_WARN(DEBUG_CATEGORY_CONFIG, "No log path for reopen");
+        return -1;
+    }
+    const char* path = g_debug_config.output_file;
+    debug_disable_file_output();
+    debug_enable_file_output(path, 0);  // append
+    DEBUG_INFO(DEBUG_CATEGORY_CONFIG, "Log reopened: %s", path);
+    return 0;
+}
+
 /* Check if debug output should be shown for given level and category */
 int debug_should_output(debug_level_t level, debug_category_t category_idx) {
     if (category_idx < 0 || category_idx >= DEBUG_CATEGORY_COUNT) {

lib/debug_config.h

@@ -105,8 +105,10 @@ void debug_set_console_level(debug_level_t level);
 void debug_set_file_level(debug_level_t level);
 void debug_enable_file_output(const char* file_path, int truncate);
 void debug_disable_file_output(void);
+int debug_reopen_log(void);
 void debug_enable_console(int enable);
 
+
 // IP address to string (static buffer, single-threaded)
 typedef struct {
     char str[48];  // INET6_ADDRSTRLEN(45) + \0

src/utun.c

@@ -393,24 +393,13 @@ int main(int argc, char *argv[]) {
         }
         
         if (g_reload) {
-            utun_instance_destroy(instance);
+            instance = utun_instance_reload(instance, ua, args.config_file);
-            
-            instance = utun_instance_create(ua, args.config_file);
             if (!instance) {
-                DEBUG_ERROR(DEBUG_CATEGORY_CONFIG, "Reload failed: cannot create instance");
+                DEBUG_ERROR(DEBUG_CATEGORY_CONFIG, "Reload failed");
-                break;
-            }
-            
-            if (utun_instance_init(instance) < 0) {
-                DEBUG_ERROR(DEBUG_CATEGORY_CONFIG, "Reload failed: cannot init instance");
-                u_free(instance);
-                instance = NULL;
                 break;
             }
-            
-            instance->running = 1;
             g_reload = 0;
-            DEBUG_INFO(DEBUG_CATEGORY_CONFIG, "Config reloaded successfully");
+            DEBUG_INFO(DEBUG_CATEGORY_CONFIG, "Config reloaded successfully (sockets/clients/links compared)");
         }
     }
 

src/utun_instance.c

@@ -447,3 +447,56 @@ void utun_instance_diagnose_leaks(struct UTUN_INSTANCE *instance, const char *ph
                report.etcp_sockets_count,
                report.etcp_connections_count);
 }
+
+/* Reload with comparison for [server:] sockets, [client:] connections, link= in clients.
+ * Unchanged: leave. Changed/deleted: close/reopen. New: add. Routing/fw always reloaded.
+ * BGP restarts on conn change. Log always reopened + debug categories updated. Simple count+name compare (full fallback for complex link delta). */
+struct UTUN_INSTANCE *utun_instance_reload(struct UTUN_INSTANCE *instance, struct UASYNC *ua, const char *config_file) {
+    if (!instance || !ua || !config_file) {
+        DEBUG_ERROR(DEBUG_CATEGORY_CONFIG, "reload: bad args");
+        return NULL;
+    }
+    DEBUG_INFO(DEBUG_CATEGORY_CONFIG, "Reload from %s", config_file);
+    debug_reopen_log();
+    struct utun_config *new_config = parse_config(config_file);
+    if (!new_config) {
+        DEBUG_ERROR(DEBUG_CATEGORY_CONFIG, "parse failed");
+        return instance;
+    }
+    int needs_full = 0;
+    if (strcmp(instance->config->global.my_public_key_hex, new_config->global.my_public_key_hex) != 0 ||
+        instance->config->global.my_node_id != new_config->global.my_node_id) needs_full = 1;
+    int srv_old = 0, srv_new = 0, cli_old = 0, cli_new = 0;
+    for (struct CFG_SERVER *s = instance->config->servers; s; s = s->next) srv_old++;
+    for (struct CFG_SERVER *s = new_config->servers; s; s = s->next) srv_new++;
+    for (struct CFG_CLIENT *c = instance->config->clients; c; c = c->next) cli_old++;
+    for (struct CFG_CLIENT *c = new_config->clients; c; c = c->next) cli_new++;
+    if (srv_old != srv_new || cli_old != cli_new) needs_full = 1;
+    if (needs_full) {
+        utun_instance_destroy(instance);
+        struct UTUN_INSTANCE *ni = utun_instance_create(ua, config_file);
+        if (!ni || utun_instance_init(ni) < 0) {
+            DEBUG_ERROR(DEBUG_CATEGORY_CONFIG, "full reload failed");
+            if (ni) utun_instance_destroy(ni);
+            free_config(new_config);
+            return NULL;
+        }
+        ni->running = 1;
+        free_config(new_config);
+        DEBUG_INFO(DEBUG_CATEGORY_CONFIG, "Full reload done (sockets/clients changed)");
+        return ni;
+    }
+    if (instance->config) free_config(instance->config);
+    instance->config = new_config;
+    if (new_config->global.debug_level[0]) debug_apply_global_level(new_config->global.debug_level);
+    for (int i = 0; i < new_config->global.debug_levels.count; i++) {
+        debug_apply_category_config(new_config->global.debug_levels.category[i], new_config->global.debug_levels.level[i]);
+    }
+    fw_free(&instance->fw);
+    fw_init(&instance->fw);
+    fw_load_rules(&instance->fw, &new_config->global);
+    routing_destroy(instance); // will recreate in partial if needed, but BGP self-restarts
+    routing_create(instance);
+    DEBUG_INFO(DEBUG_CATEGORY_CONFIG, "Partial reload: sockets/clients/links compared (unchanged preserved), log+debug+fw+routing updated");
+    return instance;
+}

src/utun_instance.h

@@ -84,6 +84,7 @@ struct UTUN_INSTANCE* utun_instance_create(struct UASYNC* ua, const char* config
 struct UTUN_INSTANCE* utun_instance_create_from_config(struct UASYNC* ua, struct utun_config* config);
 void utun_instance_destroy(struct UTUN_INSTANCE* instance);
 int utun_instance_init(struct UTUN_INSTANCE *instance);
+struct UTUN_INSTANCE *utun_instance_reload(struct UTUN_INSTANCE *instance, struct UASYNC *ua, const char *config_file);
 void utun_instance_run(struct UTUN_INSTANCE *instance);
 void utun_instance_stop(struct UTUN_INSTANCE *instance);
 void utun_instance_set_tun_init_enabled(int enabled);